Tutorial by Examples: io

Ring is de-facto standard API for clojure HTTP applications, similar to Ruby's Rack and Python's WSGI. We're going to use it with http-kit webserver. Create new Leiningen project: lein new app myapp Add http-kit dependency to project.clj: :dependencies [[org.clojure/clojure "1.8.0&quot...

<root xmlns="http://test/"> <element xmlns:example="http://foobar/"> <example:hello_world attribute="another example" /> </element> </root> The expression /root will return nothing, because there is no non-namespaced ...

Let's say we have the following function: (defn nat-num-count [nums] (count (remove neg? nums))) We can write a spec for this function by defining a function spec of the same name: (clojure.spec/fdef nat-num-count :args (s/cat :nums (s/coll-of number?)) :ret integer? ...

The following terms describe different ways to case identifiers. Pascal Casing The first letter in the identifier and the first letter of each subsequent concatenated word are capitalized. You can use Pascal case for identifiers of three or more characters. For example: BackColor Camel Casing Th...

File app.routes Protected routes have canActivate binded to Guard import { provideRouter, Router, RouterConfig, CanActivate } from '@angular/router'; //components import { LoginComponent } from './login/login.component'; import { DashboardComponent } from './dashboard/dashboard.component'; ...

You can use the ** keyword argument unpacking operator to deliver the key-value pairs in a dictionary into a function's arguments. A simplified example from the official documentation: >>> >>> def parrot(voltage, state, action): ... print("This parrot wouldn't", ac...

Consider the following dictionaries: >>> fish = {'name': "Nemo", 'hands': "fins", 'special': "gills"} >>> dog = {'name': "Clifford", 'hands': "paws", 'color': "red"} Python 3.5+ >>> fishdog = {**fish, **dog}...

Backpressure is when in an Observable processing pipeline, some asynchronous stages can't process the values fast enough and need a way to tell the upstream producer to slow down. The classic case of the need for backpressure is when the producer is a hot source: PublishSubject<Integer> sour...

There may be situations where you have setup a pool of MySQL connections, but you have a number of queries you would like to run in sequence: SELECT 1; SELECT 2; You could just run then using pool.query as seen elsewhere, however if you only have one free connection in the pool you must wait un...

Dependencies can also be injected by setters. interface Logger { public function log($message); } class Component { private $logger; private $databaseConnection; public function __construct(DatabaseConnection $databaseConnection) { $this->databaseConnection = $...

The most important application events are: Application_Start - It is raised when the application/website is started. Application_End - It is raised when the application/website is stopped. Similarly, the most used Session events are: Session_Start - It is raised when a user first requests a page...

Laravel allows user work on multiple database connections. If you need to connect to multiple databases and make them work together, you are beware of the connection setup. You also allow using different types of database in the same application if you required. Default connection In config/dat...

[JsonObject("person")] public class Person { [JsonProperty("name")] public string PersonName { get; set; } [JsonProperty("age")] public int PersonAge { get; set; } [JsonIgnore] public string Address { get; set; } } Person person = new...

We can use the Service Container as a Dependency Injection Container by binding the creation process of objects with their dependencies in one point of the application Let's suppose that the creation of a PdfCreator needs two objects as dependencies; every time we need to build an instance of PdfCr...

TCO is only available in strict mode As always check browser and Javascript implementations for support of any language features, and as with any javascript feature or syntax, it may change in the future. It provides a way to optimise recursive and deeply nested function calls by eliminating the n...

What if you want to rollback the latest migration i.e recent operation, you can use the awesome rollback command. But remember that this command rolls back only the last migration, which may include multiple migration files php artisan migrate:rollback If you are interested in rolling back all o...

Log into your AWS Console and click on Lambda under the Services tab. Under Functions you'll be able to Create a Lambda function using the same-labeled button. You'll be shown a screen where you can select a blueprint. These are simply starting points to existing Lambda functions fo...

Using the collect() helper, you can easily create new collection instances by passing in an array such as: $fruits = collect(['oranges', 'peaches', 'pears']); If you don't want to use helper functions, you can create a new Collection using the class directly: $fruits = new Illuminate\Support\Co...

AngularJS has digest loop and all your functions in a view and filters are executed every time the digest cycle is run. The digest loop will be executed whenever the model is updated and it can slow down your app (filter can be hit multiple times, before the page is loaded). You should avoid this: ...

ngOptions is a directive that simplifies the creation of a html dropdown box for the selection of an item from an array that will be stored in a model. The ngOptions attribute is used to dynamically generate a list of <option> elements for the <select> element using the array or object o...